Ultra-high resolution scanning fiber display

ABSTRACT

One embodiment is directed to a compact system for scanning electromagnetic imaging radiation, comprising a first waveguide and a second waveguide, each of which is operatively coupled to at least one electromagnetic radiation source and configured such that output from the first and second waveguides is luminance modulated and scanned along one or more axes to form at least a portion of an image.

RELATED APPLICATION DATA

The present application is a continuation of U.S. patent applicationSer. No. 16/151,029, filed on Oct. 3, 2018, which is a continuation ofU.S. patent application Ser. No. 14/156,366, filed on Jan. 15, 2014 nowU.S. patent Ser. No. 10/151,875, which claims the benefit under 35U.S.C. § 119 to U.S. Provisional Application Ser. No. 61/752,972 filedJan. 15, 2013. The foregoing applications are hereby incorporated byreference into the present application in their entirety.

The invention described herein may be manufactured and used by or forthe United States Government for United States Government purposeswithout payment of royalties thereon or therefore.

FIELD OF THE INVENTION

The present invention relates generally to compact imaging systems foruse in capturing and/or projecting images, and more particularly toconfigurations involving image processing via a plurality of fibercores.

BACKGROUND

For the military, as well as civilian, pilot, situational awareness isof primary importance. For example, Controlled Flight Into Terrain(CFIT) incidents result from a lack of information concerning animpending catastrophic collision with the environment. Thethrough-the-cockpit view of the pilot may be impeded by visibilityconditions (dark of night, inclement weather), or because of a need tointentionally obscure the view via curtains or electronic darkening ofthe canopy to protect against directed energy threats.

Information concerning the status of aircraft systems, flight path,altitude, air speed, attitude, and numerous other flight parameters arealso critical to total situational awareness. Additionally, there is awealth of data now available to the pilot via off-board or on-boarddatabases, as in the Real Time Information In the Cockpit (RTIC)concept, including but not limited to weather info, location of hostileforces, air-to-air and surface-to-air threats, mission information, andterrain detail. Another source of information comes from high-resolutionon-board sensors, e.g. Forward Looking Infrared (FLIR) and night visionsensors. This tremendous influx of available data may be presented tothe crew either through Head Down Displays (HDDs), Head Up Displays(HUDs), or some combination of both. HDDs have the obvious disadvantagethat the pilot's head is down, rather than engaged and focused on thescene out the cockpit. HUDs are disadvantaged in that the information isonly viewable through the eyebox which is typically fixed on theaircraft's bore sight.

Head Mounted Displays (HMDs), which optically relay the output from oneor more helmet-mounted microdisplays to display images within thepilot's field-of-view (FOV), allow the pilot to remain focused outsidethe cockpit, while presenting pertinent situational data as visual cuesor symbology overlaid on top of the visual scene, or even as fullyartificial rendering of the terrain and scene outside of the cockpit inthe case of impaired visibility. Because the display system moves withthe pilots head, he/she can keep the displayed information within theirfield of view (FOV) at all times.

To fully utilize the extensive capabilities of the human visual system,an HMD should provide a large horizontal and vertical FOV, high spatialresolution, and a large color depth. In addition, luminance is veryimportant, as a see-through display must be bright enough to be able toclearly display information against a high-glare background. Aircraftairspeeds, nearby fast moving objects and information, and rapid headmovements by the pilot mean that a high frame rate is necessary as well.

The FOV of the HMD may be determined by the microdisplay image sizetogether with the viewing optics. The human visual system has a totalFOV of about 200° horizontal by 130° horizontal, but most HMDs provideon the order of 40° FOV. For synthetic vision applications, where aplethora of operational data is available, a much larger field of viewapproaching that of human visual capabilities will enable the presenceof peripheral visual cues that reduce head-scanning by the pilot andincreases their sense of self-stabilization. An angular resolution ofabout 50-60 arc-seconds is a threshold for 20/20 visual acuityperformance, and it is determined by the pixel density of themicrodisplay. To best match the capabilities of the average human visualsystem, an HMD should provide 20/20 visual acuity over a 40° by 40° FOV,so at an angular resolution of 50 arc-seconds this equates to about 8megapixels (Mpx). To increase this to a desired 120° by 80° FOV wouldrequire nearly 50 Mpx.

Because there are several HMD systems in service today, many of whichare standardized around a 12 mm diagonal image source with relay andviewing optics designed for this display size, it is useful to fit newdisplay technologies within this envelope and be essentially swappablewith the microdisplays already in place in order to be of the greatestutility.

In order to fit 8 Mpx in this 12 mm format, the pixel size may be 3microns or smaller. Current state of the art in HMD microdisplaytechnology does not offer sufficient resolution and FOV at the highframe rates needed to provide the minimum desired (20/20 acuity) visualrequirements for future pilot HMDs. The pixel density of currentlydeployed image sources, such as AMOLED, AM-LCD, and LCOS is constrainedby the minimum achievable pixel size. For each of these technologies,color display requires 3 side-by-side elements, further constrainingeffective pixel pitch and resultant angular resolution, so new enablingtechnologies must be pursued.

There is a need for improved compact imaging systems which may beutilized in various applications such as HMD applications. Variousembodiments are presented herein to address this challenge.

SUMMARY

One embodiment is directed to a compact system for scanningelectromagnetic imaging radiation, comprising a first waveguide and asecond waveguide, each of which is operatively coupled to at least oneelectromagnetic radiation source and configured such that output fromthe first and second waveguides is luminance modulated and scanned alongone or more axes to form at least a portion of an image. At least of theone of the first or second waveguides may comprise an optical fiber. Theoptical fiber may comprise a cladding and at least one core. The opticalfiber may comprise two or more cores occupying the same cladding. Theoptical fiber may be a single-mode optical fiber. The optical fiber maybe a multi-mode optical fiber. The optical fiber may be a step-indexoptical fiber. The optical fiber may be a graded-index optical fiber.The optical fiber may be a photonic crystal optical fiber. The least oneelectromagnetic radiation source may be configured to produceelectromagnetic radiation having a wavelength in the ultraviolet toinfrared range. The at least one electromagnetic radiation source may beconfigured to produce visible light electromagnetic radiation. Both thefirst and second waveguides may be co-located within the same hostmedium. The first and second waveguides may be co-located withinseparate host mediums. The system further may comprise a scanningactuator operatively coupled to at least one of the first and secondwaveguides and configured to physically displace said at least one ofthe first and second waveguides. The scanning actuator may comprise apiezoelectric actuation element. The scanning actuator may be coupled toboth of the first and second waveguides and configured to physicallydisplace them together. A first scanning actuator may be coupled to thefirst waveguide, and a second scanning actuator may be coupled to thesecond waveguide, such that the first and second waveguides may beactuated independently. The system further may comprise a first scanningactuator operatively coupled to and configured to physically displacethe first waveguide along with at least one other intercoupledwaveguide, and a second scanning actuator operatively coupled to andconfigured to physically displace the second waveguide along with atleast one other intercoupled waveguide. The first waveguide and at leastone other intercoupled waveguide may comprise a single multicore fiber.The output from the first and second waveguides may be passed to ascanning element configured to scan said output along the one or moreaxes. The scanning element may be selected from the group consisting of:a MEMS mirror scanner, a deformable membrane mirror, a scanning prism,and a scanning lens. The at least one electromagnetic radiation sourcemay comprise two independent electromagnetic radiation sources, a firstelectromagnetic radiation source operatively coupled to the firstwaveguide, and a second electromagnetic radiation source operativelycoupled to the second waveguide. The at least one electromagneticradiation source may comprise a composite source configured to inject aplurality of wavelengths of radiation into at least one of the first orsecond waveguides. The composite source may be configured to inject red,green, and blue visible light radiation wavelengths. The compositesource may comprise a plurality of individual sources operativelycoupled together with a combiner. The combiner may comprise a wavelengthdivision multiplexer. The at least one electromagnetic radiation sourcemay comprise a directly-modulatable emitter. The directly-modulatableemitter may comprise a diode laser. The directly-modulatable emitter maycomprise a light-emitting diode. The at least one electromagneticradiation source may comprise an emitter operatively coupled to amodulator. The modulator may comprise an interferometric modulator. Themodulator may comprise a Mach-Zehnder interferometric modulator. Themodulator may comprise an acousto-optical modulator. The modulator maycomprise a shutter. The output from the first and second waveguides maybe scanned in a spiral scan pattern. The image at an image plane mayhave a diameter that is larger than a combined cross sectional geometricmeasurement of the first and second waveguides. The system further maycomprise a plurality of additional waveguides, the first, second, andplurality of additional waveguides being arranged in ahexagonally-packed array configuration. Image field areas associatedwith the outputs of each of the first, second, and plurality ofadditional waveguides may be overlapped by a minimum amount determinedby a common intersection of three equal circles. In a configurationfeaturing more than one core (i.e., a socalled “multicore”configuration), the cores may be arranged in a hexagonally-packed arrayconfiguration. The system further may comprise first and second lensescoupled to the first and second waveguides such that imaging radiationtransmitted through the first and second waveguides is passed throughthe first and second lenses before being output to form the portion ofthe image. The first and second lenses may comprise gradient indexlenses. The first and second lenses may comprise refractive lenses.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a fiber scanning display being supported by a hand ofan operator.

FIG. 2 illustrates a fiber scanning display relative to a coin todemonstrate size of a particular embodiment.

FIG. 3 illustrates one embodiment of a system configuration inaccordance with the present invention.

FIG. 4 illustrates an overlapping configuration.

FIG. 5 illustrates a projected display area in accordance with oneembodiment.

FIGS. 6A and 6B illustrate a configuration wherein multiple fiberscanning displays are coupled together in an array or matrix.

FIGS. 7A and 7B illustrate conventional multicore fiber configurations.

FIG. 8 illustrates an embodiment wherein two waveguides are collocatedwithin one host medium.

FIG. 9 illustrates an embodiment wherein two waveguides are collocatedwithin two host mediums.

FIG. 10 illustrates movement of a configuration such as that illustratedin FIG. 8.

FIG. 11 illustrates movement of a configuration featuring two hostmedium/waveguide configurations similar to those depicted in FIG. 9,wherein the two host mediums are intercoupled to move together.

FIG. 12 illustrates movement of a configuration featuring two hostmedium/waveguide configurations similar to those depicted in FIG. 9,wherein the two host mediums are configured to move independently.

FIG. 13 illustrates movement of a configuration featuring two hostmedium/waveguide configurations similar to those depicted in FIG. 8,wherein the two host mediums are configured to move independently.

FIG. 14 illustrates a hexagonal packed multicore waveguideconfiguration.

FIGS. 15A and 15B illustrate multicore waveguide configurations whereinindividual cores are hexagonal packed within the multicore construct.

FIG. 16A illustrates a configuration similar to that of FIG. 12, withemissions being output from the distal ends of the waveguides.

FIG. 16B illustrates a configuration similar to that of FIG. 16A, withthe exception that emissions being output from the distal ends of thewaveguides are passed through intercoupled lenses.

DETAILED DESCRIPTION

In order to address the abovedescribed challenge, two generalconfigurations for producing a color, ultra-high definitionmicro-display (CUDM) using a Fiber Scanned Display (FSD) technology,such as those described in U.S. Pat. Nos. 6,046,720; 7,555,333;7,784,697; and U.S. patent application Ser. Nos. 11/573,118 and12/468,832, are presented herein. Each of these five references isincorporated by reference herein in its entirety. These two generalconfigurations are characterized by their ability to satisfy the minimumdesired requirements for the CUDM, the cost and complexity ofimplementation, and for their ability to meet or exceed the maximumdesired requirements. FIG. 1 illustrates an FSD configuration (4) beingheld by the hand (2) of an operator while an image (6) is projected upona nearby surface.

As described in the aforementioned references, in one embodiment, a FSDoperates by vibrating the tip of an optical fiber using a piezoelectricactuator while modulating the intensity of the light transmitted downits core to form an image. Because the singlemode core retains thecoherence of the transmitted light it acts as a point source and can beimaged to a diffraction-limited spot, the size of which is determined bythe scan lens. By imaging the scan to a plane just in front of the scanlens, a spot size smaller than 3 microns can be generated. Oneembodiment of the FSD is capable of displaying an effective 500×500lines of resolution (in actuality a tight spiral of 250 cycles producinga circular display area, such as in the embodiment of FIG. 1, element6). Pixel spacing along this spiral is a function of the pixelmodulation rate, and is 20 MHz under typical operating conditions of oneembodiment. With a mechanical scan frequency of 11.5 kHz, this resultsin a frame rate of 30 Hz, with about 2000 pixels per spiral cycle of thescan if the pixel modulation is kept constant, producing about 250,000pixels. Scan rates as high as 24 kHz have been achieved in the lab,which would allow the same resolution to be produced at about a 60 Hzframe rate. A 72 Hz frame rate can be achieved by driving the fiber atabout 28 kHz. The frame rate, resolution, and scan angle are dynamicallyadjustable by increasing or decreasing the scan frequency and scanamplitude, with frame rates between 15 Hz and 60 Hz typically achievedat varying resolutions, and scan angles as high as 120°. The FSD'sextremely small size (such as in the range of 1 mm diameter×7 mm long,as shown in the embodiment of FIG. 2, wherein an FSD 4 is shown relativeto the size of a U.S. 10 cent coin 8) lends itself well in applicationswhere size and weight are a concern, and because the drive electronics,light sources, and power can all be located remotely from the scannerhead itself, it is particularly well suited for use in HMDs. A systemconfiguration is illustrated in FIG. 3, along with an associated piezodrive signal plot and spiral scan pattern diagram. Referring to FIG. 3,an exemplary embodiment of an FSD is illustrated. Radiation sources,such as a red laser 28, green laser 30, and blue laser 32 are combinedinto a single waveguide (e.g., RGB combiner 34). The waveguide, such assinglemode optical fiber 20, relays light to the tip of the waveguide(e.g., a cantilevered fiber tip 12), where it is emitted and passesthrough optional lens assembly 10, which preferably brings the emittedlight to focus at an image plane (e.g., a spiral scanned image 14). Thewaveguide tip 12 is scanned along one or more axes by an actuator, suchas a piezoelectric tube actuator 17, such that the light emitted at thetip of the waveguide is preferably scanned in an area filling scanpattern at an image plane, such as a spiral scanned image 14. Actuator17 may be affixed to an enclosure with an attachment collar 16. A driveelectronics system 22 may generate a drive signal 24 for a piezoelectricactuator 17, to control the actuation of said actuator 17. The driveelectronics 22 may also generate a pixel modulation signal 26 tomodulate the luminance of the radiation sources 28, 30, and 32, suchthat pixels are formed at the image plane 14. In one embodiment, theactuator drive signal 24 is modulated in accordance with the exemplarypattern shown in orthogonal (x) axis plot 40, such that the signalconstitutes a sinusoidal drive signal that is amplitude modulated overtime. In one embodiment, the drive signal 24 comprises a sinusoidalsignal portion that drives one scan axis of actuator 17, as well as asecond sinusoidal signal portion that drives a second scan axis, withthe second sinusoidal drive signal being phase-shifted relative to thefirst drive signal portion such that the waveguide tip 12 sweeps througha circular scan pattern. In one embodiment, a sinusoidal drive signal 24is amplitude modulated over time to dilate and contract this circularscan pattern to form an area-filling spiral scan pattern 38.

To produce a larger display with greater total lines of resolution,while maintaining frame rate and pixel density, multiple FSDs may beassembled into a two-dimensional array. If the focusing optics are suchthat the projected field area is slightly larger than the physicaldiameter of the projector, or about 1.2 mm in diameter at the focaldistance of the optics (e.g., for a FSD module diameter of approximately1 mm), these field areas can be overlapped a minimum amount determinedby the common intersection of three equal circles (as shown, forexample, in FIG. 4, element 42; the common intersection of the circlesis at element 43; element 45 illustrates an overlapping region; element47 illustrates a nonoverlapping region), thus producing a fully filledrectangular display area. The array may then be scaled to any verticaland horizontal dimension desired. To achieve a desired 8 Mpx display ina 12 mm diagonal format (at least 3840×2048 lines of resolution), we cancreate, e.g., an 11×7 hexagonal lattice of tiled FSDs, producing anapproximately 4375×2300 line (or 10 Mpx) display; a suitable projecteddisplay area (44) embodiment is depicted in FIG. 5.

Tiling in this way produces more lines of resolution than are nativelyavailable in an individual display. An advantage to tiling slightlymagnified images projected with FSDs is that no additional opticalblending is required to conceal the boundary of the display hardware.FIG. 6A illustrates an exemplary tiled display configuration wherein anarray of 11×7 FSDs (46) are coupled to the same housing or platform (48)such that they may be moved in unison if such movement is desired in aparticular embodiment; in other embodiments, individual actuation, suchas by an FSD mechanism as shown (4), may be utilized to uniquely andindependently actuate each of the FSDs. FIG. 6B illustrates a projecteddisplay area (44) at a particular image plane that may result from sucha configuration wherein a matrix of FSDs are utilized together from acommon platform or coupling (48).

To produce a seamless image that appears to the viewer as a single,high-resolution, monolithic display, there are several importantchallenges, including geometric registration, and photometricseamlessness.

Geometric registration refers to the physical alignment of eachprojector module with its neighbors. For the scans to overlap in apredictable way, each FSD should be precisely located with respect toadjacent FSDs. For standard table-top or ceiling mounted projectors thiscan prove to be a complicated and difficult process, but for the FSDs itis a relatively simple matter of high-quality, precision machining ofthe individual scanner housings and the main assembly housing.

Several factors contribute to the uniformity of the image as perceivedby the viewer. Intra-projector luminance and chrominance refers to thevariation of brightness and color within an individual projector, butbecause the FSD scans only a single pixel using single light sources foreach color channel, luminance and chrominance should be entirely uniformfor each projector.

Inter-projector luminance and chrominance refers to the variationbetween individual projectors. Chrominance variations are typicallysmall, but luminance differences can be significant between projectors.For the FSDs, the intensity of the output from the laser diodes may beadjusted to bring the projectors into agreement with one another.

Because the FSDs scan a single pixel, the neighboring scanners' pixelsdo not physically overlap. However, perceptually, the luminance in theseregions may nearly double because the human visual system cannottemporally distinguish between the projected spots. Methods ofequalizing the brightness between tiled conventional projectors may beemployed to equalize brightness in these overlapped scanned regions.

A few technology providers, such as Corning and Nufern, offer singlemode, visible wavelength optical fibers with core sizes as small 2.1-3.5microns. However, even with a core size of 2.5 microns, the Gaussianmode field diameter is about 3.5 microns. The design of high qualityfocusing optics of the FSDs is useful to achieve a diffraction limitedspot size for the scanned pixel that falls under a 3 micron pixel sizerequired to achieve a desired resolution of the display.

Additionally, each FSD produces a curved scan field at the fiber tip,and the optical design should be optimized to sufficiently flatten thisfield while minimizing distortion and other aberrations.

In this tiled approach, the overall scan angle has been reduced tominimize overlap, maximize pixel density, and minimize the overallextent of the display. However, this results optically in a narrowereyebox (the term “eyebox” representing the volume through which anoperator can move their eye and still visualize the image; generally itis desirable to have a large eyebox) at the viewer's end. To overcomethis, in one embodiment the use of a lens, e.g., a graded-index rodlenses (“GRIN” lenses), to produce a larger numerical aperture (NA) atthe output of the tip of the scanning fiber display may be employed(FIG. 16B).

Providers such as Asahi-Kasei and Mitsubishi of Japan offer multi-coreoptical fibers or fused-tapered multi-core fibers. Because thesematerials would facilitate the possibility of scanning multiple pixelsat once (as opposed to the single pixel presently scanned), the totalresolution of at the image plane can be increased for a given scanfrequency, and the effective frame rate may be increased whilemaintaining or even increasing the spatial resolution of the display.FIGS. 7A and 7B illustrate embodiments of available multi-core opticalfiber configurations (FIG. 7A illustrates a cross-sectional view 50 of amulti-core configuration; FIG. 7B illustrates a side view 52 of atapered multi-core configuration).

The abovedescribed technologies facilitate an ultra-high resolutiondisplay that supports a large FOV in a head-mounted or other near-to-eyedisplay configuration.

With regard to tiling, the images produced by the fiber-scanned displaymodules can be seamlessly tiled to form a continuous composite image.When the scanned images from each individual FSD in the tiled arrayimages are partially overlapped, the intersection of the scan fieldswill result in regions of increased luminance, i.e., the composite imagewill contain luminance non-uniformities. To provide greater luminanceuniformity in the composite image, a number of methods may be employed,including blanking overlapping pixels and/or modulating the luminancelevel of the FSDs in these regions (e.g., reducing the luminance of eachscanner at a given pixel by 50%, when two scanners are addressing thesame image area, so the luminance sums to 100% of the desired luminancelevel).

In a multiple FSD configuration, the multiple FSDs preferably arepositioned in a tiled array using precision fabrication techniques. Forseamless integration, the separation distance between the fibercenterlines is tightly controlled, as is the orientation of theactuation axes on the piezoelectric actuator tubes.

Very small variations within the mechanical tolerances of the opticalfiber (diameter, core/cladding concentricity, core size, circularity ofthe fiber cross-section) may result in variations in the mechanicalbehavior between fiber scanners. In a preferred embodiment, the drivesignal to each actuator is customized to compensate for such mechanicalvariations between optical fibers in the array.

In one embodiment, the FSDs in an array may be synchronized to reduceany perceivable temporal or spatio-temporal artifacts such as flicker orimage tearing for moving images.

With regard to scan optics, the preferred embodiments of the FSD producea curved scan field at the tip of fiber, so the optical system thatrelays the image to the eye preferably performs a field-flatteningfunction (by, e.g., the inclusion of a negative lens in the opticaltrain), in addition to magnification. The fiber optics and subsequentscan optics also preferably maximize the object-side numerical aperture(NA) to support a large eye box to a viewer. Increasing the NA alsoreduces the spot size at the image plane, enabling more pixels to bedensely packed within a small region of the image plane. Standard fibercan provide a starting mode field diameter of 3-4 microns for visiblelight. By adding a lens to the tip of the fiber (e.g., a conventionalcurved lens or a graded-index GRIN lens) as illustrated in FIG. 16B, theNA from the fiber is increased (and thereby the spot size or “mode fielddiameter at the tip is reduced). By adding a strong lens at the tip, amode field diameter of 0.6 microns can be provided near the tip of thefiber. In comparison, alternative display technologies such as liquidcrystal on silicon and LED are currently limited to a pixel pitch ofabout 4-5 microns. GRIN lenses can be fabricated separately and fuseddirectly to the fiber tip.

In one embodiment employing multi-core fiber, the multiple cores may bescanned to produce a well-filled image plane the image quality of whichis not degraded by noticeable gaps in the image. The quantity of, andspacing between, fiber cores interacts with the density of the scanpattern. A larger number of cores can be scanned in a sparser scanpattern (i.e., a large distance between scan lines) while maintaining awell-filled image. Conversely, a smaller number of cores is preferablyscanned with a denser scan pattern (i.e., a smaller distance betweenscan lines) to provide a well-filled image. In one embodiment, the coresof the multi-core fiber are tiled in a hexagonal packing, providing theadvantage of minimizing the distance between a large number of cores(e.g., FIGS. 7A, 15A, and 15B).

In two waveguides that are very close together, for instance adjacentcores in multi-core optical fiber, light transmitted through one corecan partially cross-couple to the adjacent mode through an evanescentmode. Such evanescent mode behavior can generate crosstalk between theimage content being carried by adjacent cores, if they are positionedvery close together. In a preferred embodiment, the cores are separatedby a minimum distance to minimize crosstalk between fiber cores to alevel not easily detectable by a human observer, to maintain high imagequality. Alternatively or additionally, opaque material can beincorporated into the cladding between fiber cores, to reduce crosstalkfor more closely spaced fibers.

It is important to emphasize that though the foregoing describes twoapproaches in relative isolation, an array of multiple scanned fibersand a single scanned multi-core fiber (containing an array of fibercores), these approaches represent points on a design continuum. Inanother preferred embodiment, the approaches are combined, with an arrayof multiple multi-core fibers being scanned to form a compositehigh-resolution image (e.g., FIG. 13). By collecting sets of corestogether within multi-core fibers, the number of moving parts can beminimized and manufacturing complexity can be reduced.

In one embodiment, the image relay in the HMD or other wearable displayis a transparent element, superimposing imagery over the direct view ofthe real world. Compatible HMD viewing optics include, but are notlimited to, refractive systems, reflective, diffractive, substrateguided optics.

The technologies described herein facilitate high resolution,lightweight and unobtrusive HMDs and enable virtual and augmentedreality visual systems for everything from gaming and personalentertainment systems to workspace collaboration and real worldnavigation and information systems and high performance avionicsdisplays. Preferably, an HMD should be comfortable, attractive, andvirtually indistinguishable from normal eyewear.

Referring to FIG. 8, an embodiment is depicted wherein two or morewaveguides (54, 56) are coupled to, or co-located within, the same hostmedium (58). FIG. 9 illustrates an embodiment wherein each of twowaveguides (54, 56) are coupled to their own independent host medium(58, 60). Referring to FIG. 10, when a configuration such as thatillustrated in FIG. 8 is controllably moved (illustrated as a dashedcounterposition 62), such as by a piezoelectric actuation element asdescribed above in reference to FSD systems, both waveguides (54, 56)move, or scan, together. Referring to FIG. 11, when two configurationssuch as that depicted in FIG. 9 are operatively coupled to each other,such as by a common housing or coupling member, they move, or scan,together (movement illustrated as dashed counterpositions 62, 64).Alternatively, referring to FIG. 12, independently actuated (such as bypiezoelectric actuation elements) host medium platforms (58, 60) mayindependently move their intercoupled waveguides (54, 56), as shown inFIG. 12 with the waveguides moving (62, 64) in opposite directions atthe time of the illustration. FIG. 13 illustrates a configurationanalogous to that of FIG. 12, with the exception that each of theindependently actuated host medium/waveguide constructs of FIG. 13contains more than one waveguides per medium (e.g., a multi-core opticalfiber) such that different waveguides within a given host medium (58,for example) move together, while they may move completely independentlyrelative to the waveguides coupled to the other host medium (60).

Referring to FIG. 14, a hexagonal-packed (84) configuration of multicorewaveguides (70, 72, 74, 76, 78, 80, 82) is illustrated. As describedabove hexagonal packing may be preferred for high cross sectionaldensity. Referring to FIGS. 15A and 15B, the individual cores (86, 88,90, 92, 94, 96, 98) within a multicore fiber configuration (70) may alsobe hexagonally packed (78). The configuration of FIG. 15A shows a groupof seven individual cores packed in a hexagonal (84) configuration; theconfiguration illustrates that any number of individual cores, such asthe depicted plurality (100), may be hexagonally packed (84) for desiredcross sectional density.

Referring to FIG. 16A, a configuration similar to that of FIG. 12 isdepicted with emissions (106, 108) coming out of the output ends (102,104) of the waveguides (54, 56) with relatively low emission numericalaperture configurations. To optimize possible display resolution and/orincrease the size of an eyebox provided to a viewer, the numericalapertures may be increased by using lenses; in one embodiment, asillustrated in FIG. 16B, lenses (114, 116), such as GRIN lenses (asdescribed above), may be utilized to increase numerical apertures of theoutput emissions (110, 112).

Various exemplary embodiments of the invention are described herein.Reference is made to these examples in a non-limiting sense. They areprovided to illustrate more broadly applicable aspects of the invention.Various changes may be made to the invention described and equivalentsmay be substituted without departing from the true spirit and scope ofthe invention. In addition, many modifications may be made to adapt aparticular situation, material, composition of matter, process, processact(s) or step(s) to the objective(s), spirit or scope of the presentinvention. Further, as will be appreciated by those with skill in theart that each of the individual variations described and illustratedherein has discrete components and features which may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the presentinventions. All such modifications are intended to be within the scopeof claims associated with this disclosure.

The invention includes methods that may be performed using the subjectdevices. The methods may comprise the act of providing such a suitabledevice. Such provision may be performed by the end user. In other words,the “providing” act merely requires the end user obtain, access,approach, position, set-up, activate, power-up or otherwise act toprovide the requisite device in the subject method. Methods recitedherein may be carried out in any order of the recited events which islogically possible, as well as in the recited order of events.

Exemplary aspects of the invention, together with details regardingmaterial selection and manufacture have been set forth above. As forother details of the present invention, these may be appreciated inconnection with the above-referenced patents and publications as well asgenerally known or appreciated by those with skill in the art. The samemay hold true with respect to method-based aspects of the invention interms of additional acts as commonly or logically employed.

In addition, though the invention has been described in reference toseveral examples optionally incorporating various features, theinvention is not to be limited to that which is described or indicatedas contemplated with respect to each variation of the invention. Variouschanges may be made to the invention described and equivalents (whetherrecited herein or not included for the sake of some brevity) may besubstituted without departing from the true spirit and scope of theinvention. In addition, where a range of values is provided, it isunderstood that every intervening value, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the invention.

Also, it is contemplated that any optional feature of the inventivevariations described may be set forth and claimed independently, or incombination with any one or more of the features described herein.Reference to a singular item, includes the possibility that there areplural of the same items present. More specifically, as used herein andin claims associated hereto, the singular forms “a,” “an,” “said,” and“the” include plural referents unless the specifically stated otherwise.In other words, use of the articles allow for “at least one” of thesubject item in the description above as well as claims associated withthis disclosure. It is further noted that such claims may be drafted toexclude any optional element. As such, this statement is intended toserve as antecedent basis for use of such exclusive terminology as“solely,” “only” and the like in connection with the recitation of claimelements, or use of a “negative” limitation.

Without the use of such exclusive terminology, the term “comprising” inclaims associated with this disclosure shall allow for the inclusion ofany additional element—irrespective of whether a given number ofelements are enumerated in such claims, or the addition of a featurecould be regarded as transforming the nature of an element set forth insuch claims. Except as specifically defined herein, all technical andscientific terms used herein are to be given as broad a commonlyunderstood meaning as possible while maintaining claim validity.

The breadth of the present invention is not to be limited to theexamples provided and/or the subject specification, but rather only bythe scope of claim language associated with this disclosure.

What is claimed:
 1. A system for scanning electromagnetic imagingradiation, comprising: a drive electronics system configured to generateat least one pixel modulation signal; at least one electromagneticradiation source configured to modulate an intensity of at least onepixel within an image light output by the at least one electromagneticradiation source based on the at least one pixel modulation signal; afirst waveguide optically coupled to the at least one electromagneticradiation source and configured to transmit the image light output toproduce a first projected field area of light; and a second waveguideoptically coupled to the at least one electromagnetic radiation sourceand configured to transmit the image light output to produce a secondprojected field area, wherein the pixel modulation signal is configuredto luminance modulate the at least one pixel intensity from the at leastone electromagnetic radiation source to at least one of the firstwaveguide or second waveguide concurrent with the first projected fieldarea sharing an overlapping area with the second projected field area.2. The system of claim 1, wherein the pixel intensity is increased whenthe pixel is displayed outside the overlapping area.
 3. The system ofclaim 1, wherein the pixel intensity is decreased when the pixel isdisplayed within the overlapping area.
 4. The system of claim 1, whereina luminance within the overlapping area is substantially equal to aluminance within the first and second projected areas outside theoverlapping area.
 5. The system according to any one of claim 2 or 3,wherein a luminance within the overlapping area is substantially equalto a luminance within the first and second projected areas outside theoverlapping area.
 6. The system of claim 1, wherein at least of the oneof the first or second waveguides comprises an optical fiber.
 7. Thesystem of claim 2, wherein the optical fiber comprises a cladding and atleast one core.
 8. The system of claim 3, wherein the optical fibercomprises two or more cores occupying the same cladding.
 9. The systemof claim 2, wherein the optical fiber is a single-mode optical fiber.10. The system of claim 2, wherein the optical fiber is a multi-modeoptical fiber.
 11. The system of claim 2, wherein the optical fiber is astep-index optical fiber.
 12. The system of claim 2, wherein the opticalfiber is a graded-index optical fiber.
 13. The system of claim 1,wherein the at least one electromagnetic radiation source produceselectromagnetic radiation having a wavelength in the ultraviolet toinfrared range.
 14. The system of claim 13, wherein the at least oneelectromagnetic radiation source produces visible light electromagneticradiation.
 15. The system of claim 1, further comprising a scanningactuator operatively coupled to at least one of the first and secondwaveguides and configured to physically displace said at least one ofthe first and second waveguides.
 16. The system of claim 15, wherein thescanning actuator comprises a piezoelectric actuation element.
 17. Thesystem of claim 15, wherein the scanning actuator is coupled to both ofthe first and second waveguides and configured to physically displacethem together.
 18. The system of claim 1, wherein a first scanningactuator is coupled to the first waveguide, and wherein a secondscanning actuator is coupled to the second waveguide, such that thefirst and second waveguides may be actuated independently.
 19. Thesystem of claim 1, further comprising a scanning element configured toreceive the first and second projected field areas from the first andsecond waveguides and scan said first and second projected field areasalong the one or more axes.
 20. The system of claim 19, wherein thescanning element is selected from the group consisting of: a MEMS mirrorscanner, a deformable membrane mirror, a scanning prism, and a scanninglens.
 21. The system of claim 1, wherein the at least oneelectromagnetic radiation source comprises two independentelectromagnetic radiation sources, a first electromagnetic radiationsource operatively coupled to the first waveguide, and a secondelectromagnetic radiation source operatively coupled to the secondwaveguide.
 22. The system of claim 1, wherein the at least oneelectromagnetic radiation source comprises a composite source configuredto inject a plurality of wavelengths of radiation into at least one ofthe first or second waveguides.
 23. The system of claim 22, wherein thecomposite source is configured to inject red, green, and blue visiblelight radiation wavelengths.
 24. The system of claim 23, wherein thecomposite source comprises a plurality of individual sources operativelycoupled together with a combiner.
 25. The system of claim 24, whereinthe combiner comprises a wavelength division multiplexer.
 26. The systemof claim 1, wherein the at least one electromagnetic radiation sourcecomprises a directly-modulatable emitter.
 27. The system of claim 26,wherein the directly-modulatable emitter is a diode laser.
 28. Thesystem of claim 26, wherein the directly-modulatable emitter is alight-emitting diode.
 29. The system of claim 1, wherein the at leastone electromagnetic radiation source comprises an emitter operativelycoupled to a modulator.
 30. The system of claim 29, wherein themodulator is an interferometric modulator.
 31. The system of claim 30,wherein the interferometric modulator is a Mach-Zehnder interferometricmodulator.
 32. The system of claim 29, wherein the modulator is anacousto-optical modulator.
 33. The system of claim 29, wherein themodulator is a shutter.